This invention relates to semiconductor devices and more specifically relates to a process for the low cost manufacture of a novel semiconductor device.
Semiconductor devices and housings are well known. In prior art devices, the housing area is frequently a large multiple of the area of the semiconductor device. Further, in many known semiconductor device packages, heat is taken out only from one side of the die, usually the bottom surface. Further, in present packages the manufacturing process is costly, using single device handling techniques.
More specifically, in present semiconductor devices, particularly power MOSgated devices, the top contact (the source) is generally an aluminum contact containing about 1.0% silicon (hereafter an aluminum contact). The aluminum contact is used because it is well adapted to the wafer manufacturing process. However, it is difficult to form electrical connections to such aluminum contacts so a wire bond process is usually used in which a wire is ultrasonically bonded to the underlying aluminum contact. These wire-bond connections have a limited area and are thus a source of electrical resistance (RDSON) and of heat generation during operation. However, the bottom drain contact is frequently a trimetal which is easily solderable or otherwise electrically connectable to a wide area contact surface without wire bonding as shown, for example, in U.S. Pat. No. 5,451,544. Heat is primarily removed from the silicon die at the back contact surface, even though most heat is generated at the junction in the top surface and at the wire bonds.
It is further known that solderable top contacts can be made to the top surface of a die, as shown in U.S. Pat. No. 5,047,833. However, the packages used for such solderable top contact structures have had very large “footprints” in comparison to the die area.
It would be desirable to produce a package design and process for its manufacture which would use a smaller package for the same die, while improving electrical characteristics such as RDSON of a MOSgated semiconductor type device. It would be further desirable to produce such devices in a process which permits batch handling with reduced equipment on the production line and lower costs.